| Message ID | 20220721191526.374152-5-paul@crapouillou.net (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | iio: afe/rescale improvements | expand |
Hi! 2022-07-21 at 21:15, Paul Cercueil wrote: > Implement write_raw by converting the value if writing the scale, or > just calling the managed channel driver's write_raw otherwise. > > Signed-off-by: Paul Cercueil <paul@crapouillou.net> > --- > drivers/iio/afe/iio-rescale.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c > index 5c9970b93384..0edb62ee4508 100644 > --- a/drivers/iio/afe/iio-rescale.c > +++ b/drivers/iio/afe/iio-rescale.c > @@ -141,6 +141,27 @@ int rescale_process_offset(struct rescale *rescale, int scale_type, > } > } > > +static int rescale_write_raw(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, > + int val, int val2, long mask) > +{ > + struct rescale *rescale = iio_priv(indio_dev); > + unsigned long long tmp; > + > + switch (mask) { > + case IIO_CHAN_INFO_SCALE: > + tmp = val * 1000000000LL; > + do_div(tmp, rescale->numerator); > + tmp *= rescale->denominator; > + do_div(tmp, 1000000000LL); do_div is for unsigned operands. Can val never ever be negative? What about the numerator and denominator, can those be negative? I think this code should live in a new rescale_process_inverse_scale function, or something like that (and a few tests could be added to drivers/iio/test/iio-test-rescale.c) > + return iio_write_channel_attribute(rescale->source, tmp, 0, > + IIO_CHAN_INFO_SCALE); > + default: What if the source driver has a .write_raw_get_fmt callback? That bit of info is silently dropped (with no comment that a shortcut has been taken). How does inverse rescaling mix with a .write_raw_get_fmt that returns e.g. IIO_VAL_INT_PLUS_MICRO_DB anyway? I think all cases might get a bit hairy to support, so I think you need to do some filtering and somehow fail the .write_raw call if the .write_raw_get_fmt of the source returns something that gets too difficult to support. Cheers, Peter > + return iio_write_channel_attribute(rescale->source, > + val, val2, mask); > + } > +} > + > static int rescale_read_raw(struct iio_dev *indio_dev, > struct iio_chan_spec const *chan, > int *val, int *val2, long mask) > @@ -250,6 +271,7 @@ static int rescale_read_avail(struct iio_dev *indio_dev, > } > > static const struct iio_info rescale_info = { > + .write_raw = rescale_write_raw, > .read_raw = rescale_read_raw, > .read_avail = rescale_read_avail, > };
Hi Peter, Le ven., juil. 22 2022 at 00:16:36 +0200, Peter Rosin <peda@axentia.se> a écrit : > Hi! > > 2022-07-21 at 21:15, Paul Cercueil wrote: >> Implement write_raw by converting the value if writing the scale, or >> just calling the managed channel driver's write_raw otherwise. >> >> Signed-off-by: Paul Cercueil <paul@crapouillou.net> >> --- >> drivers/iio/afe/iio-rescale.c | 22 ++++++++++++++++++++++ >> 1 file changed, 22 insertions(+) >> >> diff --git a/drivers/iio/afe/iio-rescale.c >> b/drivers/iio/afe/iio-rescale.c >> index 5c9970b93384..0edb62ee4508 100644 >> --- a/drivers/iio/afe/iio-rescale.c >> +++ b/drivers/iio/afe/iio-rescale.c >> @@ -141,6 +141,27 @@ int rescale_process_offset(struct rescale >> *rescale, int scale_type, >> } >> } >> >> +static int rescale_write_raw(struct iio_dev *indio_dev, >> + struct iio_chan_spec const *chan, >> + int val, int val2, long mask) >> +{ >> + struct rescale *rescale = iio_priv(indio_dev); >> + unsigned long long tmp; >> + >> + switch (mask) { >> + case IIO_CHAN_INFO_SCALE: >> + tmp = val * 1000000000LL; >> + do_div(tmp, rescale->numerator); >> + tmp *= rescale->denominator; >> + do_div(tmp, 1000000000LL); > > do_div is for unsigned operands. Can val never ever be negative? > What about the numerator and denominator, can those be negative? I > think this code should live in a new rescale_process_inverse_scale > function, or something like that (and a few tests could be added to > drivers/iio/test/iio-test-rescale.c) I can do that. > >> + return iio_write_channel_attribute(rescale->source, tmp, 0, >> + IIO_CHAN_INFO_SCALE); >> + default: > > What if the source driver has a .write_raw_get_fmt callback? That bit > of info is silently dropped (with no comment that a shortcut has been > taken). How does inverse rescaling mix with a .write_raw_get_fmt that > returns e.g. IIO_VAL_INT_PLUS_MICRO_DB anyway? I think all cases might > get a bit hairy to support, so I think you need to do some filtering > and somehow fail the .write_raw call if the .write_raw_get_fmt of the > source returns something that gets too difficult to support. If the inverse rescale uses the same code as rescale_process_scale() then it becomes problematic, yes, as it likes to change the type of the value. What I could try - compute the inverse of the value, then find the closest scale value+type that the source driver supports, and use this as the value+type. Then the only failure point would be if .write_raw_get_fmt returns something different than the formats returned by .read_avail, but that sounds unlikely to happen. Cheers, -Paul >> + return iio_write_channel_attribute(rescale->source, >> + val, val2, mask); >> + } >> +} >> + >> static int rescale_read_raw(struct iio_dev *indio_dev, >> struct iio_chan_spec const *chan, >> int *val, int *val2, long mask) >> @@ -250,6 +271,7 @@ static int rescale_read_avail(struct iio_dev >> *indio_dev, >> } >> >> static const struct iio_info rescale_info = { >> + .write_raw = rescale_write_raw, >> .read_raw = rescale_read_raw, >> .read_avail = rescale_read_avail, >> };
diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c index 5c9970b93384..0edb62ee4508 100644 --- a/drivers/iio/afe/iio-rescale.c +++ b/drivers/iio/afe/iio-rescale.c @@ -141,6 +141,27 @@ int rescale_process_offset(struct rescale *rescale, int scale_type, } } +static int rescale_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int val, int val2, long mask) +{ + struct rescale *rescale = iio_priv(indio_dev); + unsigned long long tmp; + + switch (mask) { + case IIO_CHAN_INFO_SCALE: + tmp = val * 1000000000LL; + do_div(tmp, rescale->numerator); + tmp *= rescale->denominator; + do_div(tmp, 1000000000LL); + return iio_write_channel_attribute(rescale->source, tmp, 0, + IIO_CHAN_INFO_SCALE); + default: + return iio_write_channel_attribute(rescale->source, + val, val2, mask); + } +} + static int rescale_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan, int *val, int *val2, long mask) @@ -250,6 +271,7 @@ static int rescale_read_avail(struct iio_dev *indio_dev, } static const struct iio_info rescale_info = { + .write_raw = rescale_write_raw, .read_raw = rescale_read_raw, .read_avail = rescale_read_avail, };
Implement write_raw by converting the value if writing the scale, or just calling the managed channel driver's write_raw otherwise. Signed-off-by: Paul Cercueil <paul@crapouillou.net> --- drivers/iio/afe/iio-rescale.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)